Inertia Property Comprehensive Measurement And Error Analysis Of Large Objects

Inertia property (mass, center of mass, inertia tensor) of large objects are keyparameters that affect their control stability. For objects with large complex shapes,inertia parameters determine the accuracy of orbit injection and space attitude, so theymust be measured with high precision. Due to structure reasons, large objects can’t beoverturned or upside down, so all parameters are obtained with a single test. The thesisis based on the research status of home and abroad. Test rigs structure and measurementprinciples are elaborated. The solution to inertia equation and error analysis are donewith coordinate conversion, MONTE CARLO method and FEA. Experiment shows thatfix position, sensor distribution, tilt angle have greater effect on precision. The momentof inertia around z axis have greater precision than that around x and y axes. Thefollowing work is done:Firstly, the moment of inertia research status of home and abroad is investigatedand the necessity of precise measurement is analyzed. Aiming at measurementdifficulties, the single test method is introduced.Secondly, the rigid body kinetics theory is summarized, which provides afoundation for deriving and solving inertia equations. From the premise of a single test,the center of mass formula is derived with graphic method. And characteristics of thesingle test is also described from principle, structure and measurement precision.Thirdly, the solid model is established by Pro/E; structures of each mechanical partand comprehensive measurement steps are elaborated; the electrical deduction part, dataprocessing system and database are analyzed. Moment of inertia measurement programsare written with DELPHI.Next, parameter solutions under linear and nonlinear model are researched. Inertiaexpressions are given with matrix theory and coordinate transformation. Besides, thephase plane method is also adopted.Then, control characteristics of the turntable is researched. Correlation andsensitivity coefficient under different angles are calculated. Results show that centroiddeviation is small when the angle is between45°and90°.Finally, error analyses are done according to experiment data and the errorquantitative calculation is done. The least square method is used as compensation. Tips for improvement are given.